French car maker PSA Group is the latest European carmaker to face scrutiny over its vehicles’ pollution levels, after a recent study conducted by the European Commission’s in-house research centre showed anomalies in emission results, French daily Le Parisien reported on 16th January.

PSA, which manufactures Peugeot and Citroën cars, has sent Vice President Christian Chapelle to Ispra in Northern Italy for a meeting on 17th January with the European Commission’s Joint Research Centre to explain the suspicious results of a study on Citroën’s C4 Cactus Blue HDI 100. According to the study, conducted over the summer in Italy and Spain and provided to the manufacturer in December, the tested model expelled 585 milligrams of nitrogen oxides per kilometre when tested on the road, more than seven times higher than its promised 80 milligrams.

Further lab tests, however, raised more suspicions. When tested outside normal benchmark temperatures (17-23°C), the car recorded nitrogen oxide emissions three times higher than allowed, according to the French newspaper. PSA denied it had used software to cheat on its emissions claims, but did not provide an explanation for the results, Le Parisien reported.

Last week, the US Environmental Protection Agency accused Fiat Chrysler of installing software to hide nitrogen oxide emissions. Besides this, French prosecutors opened a probe into possible emissions cheating by Renault. French Environment Minister Ségolène Royal said on 15th January in an interview with Journal du Dimanche that “a number of anomalies were noted on Renault vehicles. The controls performed far exceeded the permissible standards. This is also the case for other carmakers to a different extent. So, there could be other investigations.”

Besides Volkswagen, Renault is the only carmaker so far to be referred for possible criminal investigation in France over suspected breaches of emissions rules. “I have no reason to think that Renault cheated like Volkswagen,” Royal said. In Europe, most cars emit more when tested on the road as opposed to the lab, mainly as a result of dated testing procedures. The EU is in the process of reforming its laws to have all cars tested in real driving conditions. However, PSA’s case stands out due to the anomalies found even in laboratory conditions.